Persistent hypertension in Thai children: etiologies and outcome

A retrospective study was done in 66 children (0.21% of all admitted children) below the age of 18 years with persistent hypertension diagnosed at the Department of Pediatrics, Faculty of Medicine Siriraj Hospital from Jan 1999 to Dec 2003. Male to female ratio was 1.4:1 with 54.5% aged between 6-12 years old and 9.1% aged less than 1 year. Hypertension was found to be severe (BP more than the 99th percentile for age, sex and height) in 79.1% but most (78.6%) of the patients did not have symptoms related to hypertension. Chronic headaches were found in 10%, hypertensive encephalopathy in 8.6%, epistaxis in 1.4% and visual disturbance in 1.4%. The most common cause of hypertension was renal parenchymal diseases (62.7%) mainly lupus nephritis (26.9%), idiopathic nephrotic syndrome (16.4%) and chronic renal failure (16.4%). Other causes of hypertension included renovascular diseases (7.5%), drug-induced (7.5%), essential (7.5%), tumors (4.5%), coarctation of aorta (3.0%), bronchopulmonary dysplasia (3.0%), and pheochromocytoma (1.5%). Obesity and overweight (body mass index, BMI more than 25) was found in only 10 patients (15.1%). The proportion of children with BMI more than 25 was not different between essential and secondary hypertension (p = 0.15). Left ventricular hypertrophy was noted in 7.5%, hypertensive retinopathy in 3.0%, and hypertensive encephalopathy in 9.0%. One-third of the patients had normal BP within 1 month and another 47.0% had normal BP within 6 months of diagnosis. One-fifth of the patients also needed surgical intervention for specific underlying diseases. The authors suggest that since a large number of children with hypertension have secondary hypertension, intensive investigation and prompt management should be done in all. Obesity and overweight is not reliable in the differentiation between primary and secondary hypertension. Short term outcome of hypertension is good with medications and surgery in selected cases but long term outcome is still unknown.